Re: [RFC/PATCH 0/3] sched: allow arch override of cpu power

[Nathan Lynch <ntl@pobox.com>]

Breno Leitao wrote:
> Nathan Lynch wrote:
>> There is an "interesting" quality of POWER6 cores, which each have 2
>> hardware threads: assuming one thread on the core is idle, the primary
>> thread is a little "faster" than the secondary thread.  To illustrate:
>>   
> I found this feature interesting and decided to do some tests.
> After some tests I found that the example you post really runs fast in  
> the first CPU, but a more "elaborated" application runs slower on the  
> first CPU.
> Here is a small example:
>
> # taskset 0x1 time -f "%e,  %U, %S" ./a.out ; taskset 0x2 time -f "%e,  
> %U, %S" ./a.out
> 10.77,  10.72, 0.01
> 10.53, 10.48, 0.01
>
> # taskset 0x2 time -f "%e,  %U, %S" ./a.out ; taskset 0x1 time -f "%e,  
> %U, %S" ./a.out
> 10.55,  10.50, 0.01
> 10.77, 10.72, 0.01

I've been able to duplicate your results, thanks for the testcase.
Guess I'll need to understand what's going on before continuing with
this...